The statements in this section merely provide background information related to the present disclosure. Accordingly, such statements are not intended to constitute an admission of prior art.
Powertrain systems may be configured to transfer torque originating from multiple torque-generative devices through a torque transmission device to an output member that may be coupled to a driveline. Such powertrain systems include hybrid powertrain systems and extended-range electric vehicle systems. Control systems for operating such powertrain systems operate the torque-generative devices and apply torque transfer elements in the transmission to transfer torque in response to operator-commanded output torque requests, taking into account fuel economy, emissions, drivability, and other factors. Exemplary torque-generative devices include internal combustion engines and non-combustion torque machines. The non-combustion torque machines may include electric machines that are operative as motors or generators to generate a torque input to the transmission independently of a torque input from the internal combustion engine. The torque machines may transform vehicle kinetic energy transferred through the vehicle driveline to electrical energy that is storable in an electrical energy storage device in what is referred to as a regenerative operation. A control system monitors various inputs from the vehicle and the operator and provides operational control of the hybrid powertrain, including controlling transmission operating state and gear shifting, controlling the torque-generative devices, and regulating the electrical power interchange among the electrical energy storage device and the electric machines to manage outputs of the transmission, including torque and rotational speed.
Known methods for managing transitions and stabilizing states of internal combustion engines between fueled and unfueled states and all-cylinder and cylinder deactivation states include evaluating power loss differences amongst the available engine states, wherein a transition to a new engine state may be commanded when a difference in power loss between the present state and a target state is greater than a threshold power loss. This may result in over-stabilization when a large value for the threshold power loss is selected by not realizing the benefits of transitioning when the power loss difference is small over a long duration of time. This may result in under-stabilization and engine transition busyness when a small value for the threshold power loss is selected.